For citations:

Gorbachev D.V., Ivanov V.I., Ofitserov E.P., Smirnov O.I. SOME EXTREMAL PROBLEMS OF HARMONIC ANALYSIS AND APPROXIMATION THEORY. Chebyshevskii Sbornik. 2017;18(4):139-166. (In Russ.) https://doi.org/10.22405/2226-8383-2017-18-4-139-166